By way of example, an illumination device is used in endoscopy or microscopy to illuminate a region to be observed. The illumination device can be attached to an endoscope or microscope by means of a light conducting cable, or it can be directly connected to the observation device. The light is guided within the illumination device by means of, for example, light conducting optics in the form of optical elements and/or optical waveguides. So as to ensure an optimum illumination of the region to be observed, the illumination device must provide sufficient luminous power. However, due to the high luminous power, the illumination device generates large amounts of heat which has to be dissipated so that the performance of the illumination device is not impaired.
An illumination device known from U.S. Pat. No. 6,692,431 B2 can be plugged onto a proximal end of the head of an endoscope and has a plurality of LEDs as light sources which are arranged on ribs of a metal body of the illumination device, which ribs run in the axial direction. Proximal ends of optical waveguides are arranged directly on the light emitting surfaces of the LEDs and the optical waveguides are combined to form optical waveguide bundles. The optical waveguide bundles are combined to form a fibre optic loom in the region of the distal end of the illumination device, which loom is connected to the light conducting optics of the endoscope via a light coupling-in element.
A disadvantage of the known illumination device is that the heat generated by the LEDs can only be dissipated via the axial ribs of the metal body arranged on the side of the LEDs which faces away from the proximal ends of the optical waveguides of the optical waveguide bundles. However, since the LEDs also emit heat via their light emitting surfaces, the proximal ends of the optical waveguides, which are arranged directly on the surface of the LED, heat up. This can disadvantageously impair the functionality of the optical waveguides so that the maximum luminous power of the optical waveguides is limited by the insufficient heat dissipation.
Moreover, it is disadvantageous that all light emitting surfaces of the LEDs are connected to optical waveguides for the purposes of providing light generated by the LEDs as illumination light for the endoscope. In particular, those surface regions of the LEDs which emit little light are also contacted by optical waveguides in the process; as a result of this, the maximum light intensity of the optical waveguide bundles in the case of a predetermined optical waveguide bundle cross section is reduced due to the arrangement of optical waveguides in the regions with a low light emission.